1. Field of the Invention
The present invention relates to a biodegradable sustained release preparation for treating periodontitis. More specifically, this invention relates to a biodegradable sustained release preparation for treating periodontitis characterized in that the core, which is further coated with chitosan, of the preparation contains medicine and polysaccharide, i.e. sodium alginate.
Periodontitis, an inflammation of periodontium caused by anaerobic bacteria, is a periodontal disease exacerbated from gingivitis. Because periodontitis destructs collagen supporting alveolodental membrane and dissolves alveoru, periodontal ligament are dissociated and periodontal cyst, an important clinical symptom, is invaded. In serious symptom, teeth are lost. The pathogenetic bacteria causing periodontitis are mostly gram-negative anaerobic bacteria. Those bacteria destruct desmoplasm and periodontal ligament of alveolodental membrane a side effect of migrating polymorphonuclear cell depravates inflammation.
2. Description of the Prior Art
The general therapy of periodontitis in the prior art includes apparatotherapy such as scaling, curettage or root planing. However, these therapies are used only as a supplementary method due to high recurrens. Therefore, in order to treat periodontitis, pharmacotherapy have to be used primarily.
Examples of pharmacotherapy includes antibiotic therapy for controlling gram-anaerobic bacteria and therapy of using antiphlogistic for laxation of inflammation. Among the various antibiotics, tetracycline-type medicines are preferred because they are used widely and have low toxicity for human beings. Since the MIC (minimum inhibition concentration) 90% value is 8 .mu.g/ml, the effectiveness of these medicines is high enough to be maintained for 6 months per only a dose.
With regard to antibiotic therapy, in case of systemic medication, since an excessive amount of antibiotics have to be used for maintaining the effective concentration of medicine in the palatal bursa of gingiva, the side effect and manifestation of tolerance are occurred.
Alternatively, in case of the generally preferred topical therapy, oral irrigation is preferred in order to administrate the antibiotics topically. However, this therapy is unsuitable because the medicine can not satisfactorily pass through periodontal cyst. Also, a method of direct injection of medicine with a syringe is only effective for a short-term-therapy but not for a long-term therapy.
In these circumstances, a sustained release preparation which can slowly release medicine in periodontal cyst by inserting a carrier into periodontal cyst has been recently developed in order to solve these problems.
This method has been disclosed in the documents as follows: U.S. Pat. No. 3,911,099 capsules and tablets of prolonged effects; U.S. Pat. No. 4,020,518 a buccal implant of which medicine is released by saliva; U.S. Pat. No. 3,679,360 topical gel; U.S. Pat. No. 3,339,546 bandages containing topical medicine; U.S. Pat. No. 3,964,164 plastic mass containing medicine; U.S. Pat. No. 3,219,527 medicated periodontal dressing; U.S. Pat. No. 3,698,392 topical dressing containing medicine dispersed in microparticulated carrier; U.S. Pat. No. 4,329,333 droplet of medicine microcapsulated; and U.S. Pat. No. 3,844,286 foam film devices containing medicine.
While collagen film containing tetracycline developed by Minabe etc., is a biodegradalde preparation of which effective concentration is prolonged over 10 days in palatal bursa of gingive, it has a disadvantage of causing immunoreaction due to hetero antigen-protein.
While filamentous devices containing medicine, described in U.S. Pat. No. 3,417,179, U.S. Pat. No. 2,667,443, U.S. Pat. No. 2,748,781 and U.S. Pat. No. 3,942,539 and hollow fiber device described in U.S. Pat. No. 4,175,326, both made of cellulose acetate, are effective in inclusion of medicine but not in control of releasing medicine.
In case of hollow fiber, the. elution of 95% of medicine is completed in 2 hours, while in case of monolith fiber, that is completed in one day. Also, monolith fiber made of ethylene vinyl acetate polymer is excellent as a sustained release preparation because the elution of medicine is prolonged for 9 days.
However, since the carrier is insoluble so that it can react as a physical promoter in inflammation reaction, and it should be removed after treatment due to its undegradability, they are disadvantageous to be used.
As a filamentous biodegradable medicine, polyglycolic acid fiber containing medicine is described in U.S. Pat. No. 3,991,766. Besides, there is soluble hydroxypropyl cellulose strip, as a soluble carrier, developed by Niguchi. Although there is not disadvantage of removing after treatment because of its high solubility, it is unsuitable for long-term therapy since the elusion of medicine is completed in 24 hours due to dissolution of carrier. Further, hydrophilic paste preparation to be injected to periodontal cyst with syringe containing tetracycline has been developed. However, the dependency between the clinical effect and change in concentration of tetracycline has not yet been determined.